1. The Field of the Invention
The present invention relates to a reenforcement insert for joints in piping and the like and in particular to a method for forming and placing such an insert.
2. The Prior Art
It is a well-known fact that joints in piping are their weakest points and that this is the main point of wear and subsequent leakage. The term "joint", as used herein, is intended to cover the part or device located at the point where a first pipe is coupled, joined, and/or connected to two or more pipes for the purposes of splitting the flow path from the original single flow path to two or more flow paths regardless of the relative proportions. The joint itself can be weakened to the point of rupture by pressures within the pipe. Also, joints are the points of highest wear when any kind of erosive material is passed through the piping. This further applies to build up of materials at the joints, which materials can also cause degeneration of the joint. Heretofore the answer to the problem of degeneration of pipe joints has been either the replacement of the joint or attempting to enclose the joint within some kind of jacketing. However, both of these approaches are often unsuitable, for example in wells.
One example of the prior art for using a mandrel to expand a pipe is U.S. Pat. No. 5,366,012 which describes a method of completing uncased sections of a borehole by placing, at a predetermined position in the borehole, a slotted liner which is provided with a plurality of overlapping slots. The upper end of the liner is fixed in place and an upwardly tapering expansion mandrel is drawn upwardly through the slotted liner expanding it outwardly to engage the walls of the borehole. Another use of a mandrel to expand pipe is U.S. Pat. No. 5,348,095 in which the mandrel is driven downwardly to expand the pipe. While these concepts may work for straight sections of piping, clearly it would not be readily adaptable for pipe joints.
Another method for creating sealing between a lining and borehole, casing or pipeline is shown in U.S. Pat. No. 5,494,106. This consists of a deformable annular seal which is put in place in a deformed or contracted state, which does not impede insertion. During expansion of the seal it is hardened to form a substantially permanent repair. However, this patent does not suggest how this technology could be applied to pipe junctions to create an improved seal, particularly at the joints and/or seams of the junction where leakage is most likely to occur.
U.S. Pat. No. 3,358,769 show another pipe lining which is inserted into the pipe in a folded or collapsed state and then set when in place. However, this patent does not suggest how such a concept could be applied to a pipe joint.
Another method for inserting a lining into a casing is shown in U.S. Pat. No. 5,454,419 in which a tubular polymeric material is lowered into the well in a stretched condition, due to a series of weights attached to the leading end When properly positioned, the weights are released and the tubular material returns to its normal condition in which it presses against the walls to the borehole. There is no suggestion of how this method could be applied to junctions with multiple legs.
The present invention provides a means to overcome problems not addressed nor solved by the prior art by providing a technique for applying a reinforcing liner to a pipe junction and, in particular, to a pipe junction which can only be reached through the bore of the pipe.